Study on Sedimentary Facies of Chang 2_1 Oil-bearing Fomation in Jiyuan District

According to analysis of core samples and logging data,it is indicated that front-delta deposition is the main sedimentary system of Chang 21 oil-bearing fomation in Jiyuan district.It includes six types of sedimentary microfacies which are the distributary channel deposits,underwater natural levee,underwater crevasse splay,river mouth bar,sheet sand and the inter-distributary channel deposits.The distributary channel deposits and river mouth bar are the good reservoirs,and also are the direction of developing in this area.The sedimentary facies analysis is the key to study the sand body distributes,determining sedimentary facies correctly or not is affecting directly to understanding sand distribution rule.